In a casting process or the like for manufacturing cast products by pouring molten metal into a casting mold, a metal melting furnace is used for melting a metal to be melted. The metal melting furnace generally employs an induction furnace system configured to pass a current to an induction coil, which is provided around a crucible for heating the metal to be melted in the crucible by generating an induction current therein. There is a known hybrid system using the induction furnace system in combination with a heating system configured to inject flames from a burner onto a metal to be melted in a crucible and melt the metal to be melted by heat of the flames (for example, see Patent Literature 1).
In the hybrid metal melting furnace of the related art, an opening of the crucible is kept opened toward the outside to allow the burner to inject flames from above the crucible. In this configuration, during a process of melting the metal to be melted, heat in the crucible dissipates through the opening, and thus probabilities of lowering of melting efficiencies and deterioration of working environment around the metal melting furnace have still been a concern even though a degree of heating is improved by employing the hybrid system.
Consequently, a configuration including a furnace lid for covering the opening of the crucible and a burner installed on the furnace lid is proposed (see Patent Literature 2). In this configuration, as the burner may inject flames toward the metal to be melted in the crucible with the opening covered with the furnace lid, heat dissipation may be restricted, and thus the above-described concern is solved.